The beta cell of the endocrine pancreas play a critical role in the pathogenesis of diabetes mellitus. A comprehensive understanding of the molecular basis of beta cell development and function should lead to new approaches for the prevention and treatment of diabetes. The overall goal of this application is the generation of genetically-defined mouse models that will facilitate the identification. The overall goal of this application is the generation of genetically-defined mouse models that will facilitate the identification and purification of pancreatic stem/progenitor cells. The aims of this application are to generate transgenic mouse models in which green fluorescent protein (GFP) and its cyan and yellow derivatives as well as DsRed fluorescent protein (DsRed) are driven by different developmentally-regulated promoters including those of the transcription factors insulin promoter factor-1, neurogenin 3 and Pax4, and the pancreatic hormones insulin and glucagon. These mouse models will be used to isolate and characterize presumptive pancreatic stem/progenitor cells. We believe these animal models will be a valuable resource for members of the Beta Cell Biology Consortium and will facilitate the identification and characterization of pancreatic stem/progenitor cells.